AFP, published on Wednesday, September 14, 2022 at 2:00 p.m.
Monogamous, southern hemisphere great albatrosses are not immune to separation, more predictable in “shy” males who prefer to avoid confrontation with a competing male, according to a study Wednesday.
“We show for the first time in a wild animal species a link between personality and divorce”, explained to AFP Ruijiao Sun, first author of the study published in the Biology Letters of the British Royal Society.
Diomedea Exulans, the great screaming albatross, is nevertheless a model of loyalty. Divorce there is “very rare”, with a rate of around 13% in the population studied by the ecologist, who is a doctoral student at the American Woods Hole Institute of Oceanography.
If 90% of birds are monogamous, sailors are all without exception. But life as a couple is not smooth, even for the latter.
Studies have identified an “adaptive” divorce regime, in specialist language, that is to say motivated by the eternal imperative of reproduction. For example, “if a bird finds that its breeding chances are too low with a specific mate, it may look for another one,” says Ruijiao Sun. One study has spotted such behavior in the black-browed albatross.
Nothing like it here. On the other hand, the personality of the individual, more or less shy, “is one of the factors predicting a divorce”, explains to AFP the marine biologist Stéphanie Jenouvrier, co-author of the study. In this case, a “shy” albatross is up to twice as likely to divorce as a “daring” albatross.
To verify this, and explain it, the researchers drew on a database unique in the world, established by the Center for Biological Studies of Chizé, – which depends on the University of La Rochelle -, and the Polar Institute French Paul-Emile Victor.
Since 1959, their members have been recording the tribulations of a colony of great albatrosses established on Possession Island, in the icy waters of the Crozet Archipelago, one of the French Southern and Antarctic Lands.
“We ring them with a number, and each year we draw up a map with the location of their nest, they are not shy and by approaching slowly we can make many observations”, says Stéphanie Jenouvrier, who has long worked for the center of Chizé.
– personality factor –
Researchers can thus “reconstruct the entire history of these birds”, from their birth to their disappearance, she explains.
Because Diomedea Exulans, which can live up to 50 years, has its habits. Once in a pair, it reproduces “every two years, because it needs a year to raise its only young, before taking a year off, but separately, before the pair reunites again” , explains Ruijiao Sun.
And this is where things get complicated. Males and females will spend months gliding, thanks to their wings with a span of more than three meters, over several hundred kilometers a day, above the waters of the southern Indian Ocean. But in distinct areas, the males further south than the females, who seek sustenance in waters more frequented by trawlers using trolling lines. And there, “if the albatross tries to catch the lure, it sinks”, explains Stéphanie Jenouvrier.
As a result, the population of great albatrosses is predominantly male, with a certain number of widowers obviously not intending to stay that way for too long. This is where the personality factor comes in. The researchers measured that of almost 2,000 individuals, over ten years, with a scale of reaction to the approach of a human up to five meters. From the most “daring”, which ignores the intruder, to the most “timid”, which abandons the nest, which is very rare.
“Some are very bold, some very shy, and most are in between,” according to Ruijiao Sun. By cross-referencing these measures with those of the divorce rate, the researchers concluded that “shy males divorce more than bold males”. A shy male in a relationship will prefer to spin the English way rather than confront a widower in need of the company of the opposite sex.
However, the personality of the protagonists does not explain everything. “Other factors are at work, remarks Stéphanie Jenouvrier, individuals who are in a long-term relationship are less likely to divorce than young couples”…